1. Field of the Invention
The invention relates to an electrical line for the connection of non-stationary electrical loads to a power source, which line has a line core surrounded by a jacket of insulating material, in which line core wires consisting of insulated electrical conductors used both for the transmission of data and for supplying power are arranged and in which the line core is surrounded by an electrical screen having two layers, one of which is constructed as braid or stranded cover layer of copper wires and the other one of which is constructed of a fleece material consisting of synthetic material made electrically conductive.
Such a line is disclosed in EP-A-1 589 541.
2. Description of Related Art
Such lines are used, for example, in drag chains and for connecting non-stationary devices, particularly robots, to a voltage or signal source. The lines must be capable of carrying mechanical loads, with a flexural strength which remains uniform for a long time. They should also remain easily bendable within a wide range of temperatures which is, for example, between −40° C. and +80° C. Apart from resistance against temperature and torsion, their electrical properties are of special significance for such lines. This refers especially to the conductors provided for the transmission of data, with operating frequencies of over 100 MHz.
Apart from other transmission elements, the known line according to DE 101 62 739 A1 has two data transmission lines and one power line used for supplying power which are in each case surrounded by an electrical screen. The data transmission lines in each case consist of a pair of wires with two insulated electrical conductors and the power line has four wires of insulated electrical conductors. This known line has been successful in practice. However, its production is complex.
In EP-A-1 589 541 mentioned initially, an electrical line for the connection of non-stationary electrical loads to a power source is described which has a line core surrounded by a jacket of insulating material, in which line core wires consisting of insulated electrical conductors are arranged which are used both for the transmission of data and for supplying power. The line core of this known line is surrounded by an electrical screen having two layers, one of which is constructed as braid or stranded cover layer of copper wires whilst the other one has at least one layer of a fleece material consisting of synthetic material and made electrically conductive. For the data transmission, a pair of wires which is surrounded by shielding is placed in the line core. In the mutually opposite interstices between the wires of the pair of wires, a supply wire each used for supplying power is arranged outside the shielding.